SEATTLE - The trade took time to materialize, even after the centerpieces became well defined.

In the days leading up to the 2012 winter meetings, the Mets realized that for all the suitors for Cy Young Award winner R.A. Dickey, there was only one that could offer the catcher of the future. And once the Blue Jays made it clear that they'd part with Travis d'Arnaud, the Mets turned their focus to rounding out the deal.

"One impact prospect was not going to do it," Mets assistant general manager John Ricco said earlier this season. "We needed a little bit more than that. So then, it's a matter of figuring out how you're going to maximize the return."

For the Mets, that meant deciding which highly regarded Blue Jays pitching prospect to pursue: Noah Syndergaard or Aaron Sanchez.

Ultimately, years will pass before the full impact of the trade can be truly evaluated for both sides. But Tuesday brought perhaps the beginnings of clarity.

With Syndergaard, 21, still attempting to settle into a rhythm at Triple-A Las Vegas, Sanchez, 22, is beginning his big-league career after being promoted Tuesday to help bolster the Blue Jays bullpen.

Back in 2012, the Blue Jays were initially hesitant to include either Sanchez or Syndergaard in a deal. The two had been taken four picks apart in the supplemental round of the 2010 draft, Sanchez at 34th overall and Syndergaard 38th.

At the time of the trade, both possessed plenty of upside, though neither had advanced past Class A. But as talks evolved, the Blue Jays proved more willing to move Syndergaard, an arrangement that suited the Mets just fine.

Syndergaard had been the preference of the Mets' scouts. Earlier this season, Paul DePodesta, the vice president of player development and scouting, said the Mets had been encouraged with Syndergaard's progress since high school.

And it was clear that he had a high ceiling -- the major prerequisite for the second piece in the Dickey deal.

Of course, Sanchez is no slouch, either. And a Mets insider acknowledged that if the Jays had been more willing to move Sanchez instead, it's likely the Mets would have found him a sufficient enough piece to still pull the trigger on the trade.

Only time will tell whether the Mets' preference for Syndergaard will ultimately prove to be correct.

As recently as spring training, Syndergaard was blowing away scouts with an explosive upper 90s fastball and a mound presence befitting a pitcher who had earned the nickname "Thor."

Sanchez began the season at Double-A New Hampshire, Syndergaard started at Las Vegas, just one step away from reaching the Show. He had been expected to arrive in New York as early as June, following in the footsteps of Zack Wheeler and Matt Harvey.